Late in the afternoon we reached Mr. Levy and Ms. Merkin and got our answers.

First things first: The photo comes from a New Yorkerarticle by Ian Parker published last summer about primatologist Frans de Waal and his work with bonobos. Mr. de Waal took the photo himself, and when Mr. Levy wrote to him asking for permission to use it on the cover of Erotomania, he agreed under the condition that Mr. Levy credit him appropriately, send him a complementary copy of the book, and allow him to write a short informational paragraph about bonobos to be printed with the front matter.

Mr. Levy agreed to these terms.

Around the same time, according to Mr. Levy, Mr. de Waal was contacted by Ms. Squire. She wanted to use the bonobos photo on the cover of her book, too. Not realizing that Ms. Squire was calling about a project unrelated to Mr. Levy’s novel, Mr. de Waal gave her the go-ahead.

"He simply got us confused, and he gave permission to us and them at the same time without realizing it," Mr. Levy said.

Mr. de Waal confirmed that story. "I received emails about this cover from both authors or publishers in the same week," he wrote in an email. "I am not a photo agency, but a busy scientist, so [I] don’t keep very careful track of this sort of request, of which I get too many. And so yes, in my mind I must have thought I was dealing with a single book, and never realized I gave two permissions."

He added, "I think it’s amusing that both decided to use the photo in about the same way, but perhaps this is dictated with the vertical format of a book cover, whereas the photo clearly is a horizontal one."

As for Ms. Merkin’s blurbs, well, it’s just kind of a coincidence. In an interview yesterday, Ms. Merkin said she and Ms. Squire have been with friends forever, and Mr. Levy she knew from sitting together on panels about psychotherapy. Both asked her to blurb their books separately, and it was she who first brought the cover problem to their attention.

We asked Ms. Merkin to explain how this photo of bonobos doing it could have possibly fit with both of these books, one of which is a raunchy erotic novel and the other is a cultural history of marriage.

"One is about the consequences of unfettered lust, and the threat it would impose to the established order," Ms. Merkin said. "The other is about the pleasures of unfettered lust versus the gratification of individualized desire, or something like that, if that makes any sense."